|Spatial and seasonal variability of pico-, nano- and microphytoplankton at the bottom seawater in the north coast of Sfax, Eastern Mediterranean Sea |
Auteur(s): Rekik Amira, Denis M., Maalej Sami, Ayadi Habib
(Article) Publié: Environmental Science And Pollution Research, vol. 22 p.15961-15975 (2015)
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In the frame of the Taparura Project, we studied thedistribution of pico-, nano- and microphytoplankton communitiesin relation to environmental variables at 18 stationssampled during four coastal cruises conducted betweenOctober 2009 and July 2010 at the bottom, on the north coastof Sfax (Tunisia, Eastern Mediterranean Sea). The restorationeffect on coastal ultraphytoplankton (<10 μm) andmicrophytoplankton (<200 μm) was investigated using conventionalflow cytometry and inverted microscopy. Flow cytometryanalysis of ultraphytoplankton resolved six groups(Prochlorococcus, Synechococcus, nanoeukaryotes and threedistinct subgroups within picoeukaryotes). In addition to theseautotrophic groups, two unknown groups were characterisedon the north coast. Picophytoplankton abundance shifted froma summer dominance of Synechococcus to a dominance ofpicoeukaryotes and Prochlorococcus during spring.Nanoeukaryotes were the most abundant in spring.Microphytoplankton was resolved into five groups, labelledBacillariophyceae, Dinophyceae, Cyanobacteriae,Euglenophyceae and Chlorophyceae. A total of 90microphytoplankton species were identified in all stations,with an overwhelming abundance of large diatoms, a typicaltrait of benthic communities (Coscinodiscus sp.,Grammatophora sp., Navicula sp., Pleurosigma sp.,Striatella unipunctata …). Results collected in this study arefavouring a beneficial impact on the ecosystem of the Sfaxnorth coast restoration achieved by the Taparura Project.